56
Human NIBP Nano
Owner’s Guide
Brachial
Finger
Finger-Brachial
Systolic
169 ± 33
163 ± 29
-5 ± 15
Diastolic
89 ± 17
81 ± 18
-9 ± 10
Mean
118 ± 22
104 ± 21
-13 ± 11
These numbers tend to vary somewhat per study, presumably because of
age diff erences of the subjects in the studies. Thus, averaged over a study
population, finger arterial mean pressure is about 10 mmHg lower than
intra-arterial pressure in the brachial artery, but individual diff erences
may be larger.
Reconstructing intra-arterial brachial pressure
The distortion of the pressure waveform along an artery can be
investigated with special mathematical techniques such as Fourier
spectra. These analyses showed that the distortion of finger arterial
pressure is caused by a resonance, a tendency of the arm arterial system
to oscillate, at about 8 Hz. The amplification of pulse pressure that is
a consequence of this resonance is attributed to a gradual decrease in
arterial diameter, to an increase arterial stiff ness of the distal arterial tree
and to wave reflections.
A method has been described to derive brachial pressure waveforms from
finger arterial pressure by means of waveform filtering [Gizdulich 1996].
Additionally, a method was developed to correct for the pressure gradient
using a regression equation. Reconstruction of brachial intra-arterial
pressure from finger arterial pressures (FinAP) has implemented in the
study of Guelen et al., 2003. As an illustration of this, see their published
data in Table A-2 below.
Diff erences between the measured intra-brachial arterial pressure and
the finger arterial pressure, uncorrected (FinAP) and corrected (reBAP) are
shown.
Systolic
(mmHg)
(mmHg)
Mean
(mmHg)
Mean
SD
Mean
SD
Mean
SD
FinAP
-9.7*
13.0
-11.6*
8.0
-16.3*
7.9
ficAP
-1.1
10.7
- 0.2
6.8
- 1.5
6.6
reBAP
3.1*
7.6+
4.0*
5.6+
2.7*
4.7+
*P<0.05 using paired Student’s t-test, +P<0.05 using F-test for variance
ratios.
Table A–1:
Pressures
and pressure differences,
(53 subjects, aged 22–83
years, all numbers in
mmHg, mean±SD).
Table A–2:
Comparison
with brachial artery
pressure. Mean
(accuracy) and standard
deviation (SD) of the
differences between the
original fi nger arterial
pressure (FinAP), the
waveform-fi ltered and
level-corrected pressure
(fl cAP), and the return-
to-fl ow calibrated
waveform-fi ltered and
level-corrected pressure
(reBAP), all compared
to the measured intra-
brachial pressure [Guelen
et al., 2003].
